Question

A rectangular coil in the plane of the paper has dimensions a andb.
A long wire that carries a current I is placed directly abovethe
coil (see FIGURE).
(a) Obtain an expression for the magnetic flux through the coil asa
function of x for .
(b) For what value of x is the flux though the coil a maximum?
Forwhat value of x is the flux a minimum? [You may opt not to
answerthis, but I'll still give you the LIFESAVER points.]